"What's
Special About This Number" Facts

eople
have always been fascinated by NUMBERS...
Numbers are actually basic elements of mathematics used for
counting, measuring, ranking, comparing quantities, and solving
equations. Numbers have unique properties: for some ones of
us they are merely concise symbols manipulated according to
arbitrary rules, for others numbers carry occult powers and
mystic virtues.
Almost all numeration systems start as simple tally
marks, using single strokes to represent each additional unit.
The first known use of numbers dates back to around 30,000 BC when
tally marks were precisely used by stone age people.
To show that each number is unique and has its own beauty, we have
collected for you a huge amount of facts pertaining to the magical
world of numbers, covering a range of different topics including mathematics, history, philosophy, psychology, symbolism, etymology, language,
and/or ethnology...

You
can now purchase “Numberopedia: What's Special
About This Number” by G. Sarcone in pdf
format! 189 pages filled with an incredible variety
of fun facts on numbers (and their peculiar properties),
both mathematical and cultural, tantalizing problems and
anecdotes. There is much to learn for everyone!
After confirmation of your order, we will email you the code
to access the corresponding download page

NaN (Not aNumber)
is, in computing, a value (or symbol) that is usually produced
as the result of an operation on invalid input operands, especially
in floating-point
calculations. NaNs are close to some undefined or inderterminate expressions
in mathematics. In short, NaN is not really a number but a symbol
that represents a numerical quantity whose magnitude cannot be
determined by the operating system. This mainly occurs when infinity and zero are
misused in expressions.

Not
all indeterminate forms produce a NaN: for instance,
the division 1/0 makes no sense in pure mathematics, but curiously
enough in IEEE
754 this fraction is, by convention, equal to +∞ (hence
1/∞ = 0). Reality is, there are no answers for expressions
such as n/0 or n/∞ (for n > 0).
For n/0 the problem we are trying to solve is simply:n = 0 x A
We cannot find any number for A since 0 x A =
0 for any whole number, rational number, real number, and so on.
Regarding the fraction n/∞, if we admit that it
is equal to 0 (when n is small but >0), then:
1 + n/∞ = 1, thus ∞ + n = ∞,
and n = 0...
Which contradicts n > 0. So, don't try to use infinity
as a real number, you will get wrong answers!

Infinity
cannot be used directly, but we can use a limit: n/∞ is
undefined, we do know however that n/x
(with, say n = 1) approaches 0 as x approaches ∞:

is a
divergent series, meaning that it lacks a sum in the usual sense...
In fact, if you treat this series like a telescoping series and/or
use different bracketing procedures to sum it, you may obtain contradictory
results...

∑

=
1 - 1 + 1 - 1 + 1 - 1 + 1 - 1 + ...

=

∑1

=
(1-1) + (1-1) + (1-1) + (1-1) + ...

=
0

∑2

=
1 + (-1+1) + (-1+1) + (-1+1) + ...

=
1

∑3

=
1 + (1-1+1-1+1-1+ ...) = 1 + ∑ => ∑

=
1/2

As shown
above, it appears to equal 0 and 1, yet in some sense 'sums' to 1/2,
producing a paradox... The error here is that the associative law
cannot be applied freely to an infinite sum unless the sum is absolutely
convergent. We can say that the sum of Grandi's series is NaN.

= i,
is the imaginary
unit of any imaginary number. Discovered by the Italian mathematician Girolamo
Cardano.
An imaginary
number is a number of the form bi where
'b' is a real number, 'i' is the square root of -1, for
b 0.
Imaginary numbers (and complex numbers in general) are essential
for describing physical reality and have concrete applications
in: electromagnetism, signal processing, control theory, quantum
mechanics, cryptology, and cartography...

is the
result of the folowing equations:
x2 + 1 = 0 (for x -i)

Square
roots of negative numbers other than -1 can be written under
the form:-n
= in

ei/2 =
cos (/2)
+ i sin (/2)
= i

i
to the i is a real number
ii= e-/2 ≈ 0.207879576...
(cf.i to
the i is a Real Number)ProofFrom
Euler's formula: eix = cos(x) + i sin(x)
Then
ei/2 =
cos(/2)
+ i sin(/2)
= i
Raising both sides to i-th power:
ei·i/2 =
e-/2 = ii,
which is approximately 0.207879576...
(Actually, this is one of many possible values for i to
the i)

In
number theory, "Wilson's theorem" states that a natural
number greater than 1 is a prime number if and only if:
(n - 1)! == -1(mod n)

Multiplying
any number by -1 is equivalent to changing the sign on the number.

x-1 =
1/x

1/(-1)
= (-1)/1

=
ei

≈ sin2017(2)1/5

0⠼⠚

is
a separate and special entity called 'Identity
element'. 0 is actually the identity element under addition
for the real numbers, since if a is any real number, a +
0 = 0 + a = a. Mathematicians refers
to 0 as the additive identity (or better said, the reflexive
identity of addition).

is considered
to be a purely imaginary number: 0 is the only complex number
which is both real and purely imaginary.

identifies
the concept of "almost" impossible in probability.
More generally, the concept of almost nowhere in measure theory.

By convention,
you cannot divide any number by zero.
In theory, zero multiplied by infinity is undetermined (as is zero
divided by zero).

It is
the only integer (actually, the only real number) that is neither
negative nor positive. The question whether 'zero' is odd or
even seems to be totally subjective!

Mathematical
equations with one or more unknown factors are solved by equalizing
them to zero.

is the
number of n x n magic squares for n =
2.

The
difference between 3, 30 and 300 is only some extra zeros, but
those little circles are actually one of the world's greatest
inventions! As early as 200 B.C., Hindu scholars were working
with nine oddly shaped symbols and
a dot that eventually would bring order out of a world of mathematical
chaos. The dot and nine symbols were the earliest known forerunners
of the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Comprised of only
ten symbols and based on multiples of ten, the Hindu numeral
system was easily learned and easily used. Who first thought
of using a dot (bindu, in sanskrit) as the tenth number
is not known. But it can be supposed that a Hindu, working on
his abacus, wanted to keep a written record of the answers on
his abacus. One day he used a symbol '.' which
he called shunya ()
to indicate a column on his counting board in which he had moved
no beads... Shunya, the dot, was originally not zero the number,
but merely a mark to indicate empty space.

The
word "zero" was coined by the Italian mathematician
Leonardo Pisano, said Fibonacci. He transformed the Arabic word
'صِفْر', sifr (from the
semitic root s.p.r., 'empty') into Italian equivalent zefiro,
shortened to zero afterwards. Many languages have adopted
the word "zero": english, catalan, french (zéro),
portuguese, romanian, spanish (cero), wallon (zérô),
albanian, polish, japanese...
Europe is divided into two regions: the 'zero region'
(see above) and the 'nullus region' (nullus,
'zero' in Latin). The 'nullus region' includes the Germanic, the
Skandinavian and some Slavonic countries. The following is a table
of the number 0 in a sample of the languages of the 'nullus region':

Dutch

nul

Czech

nula

German

null

Russian

nol'

Swedish

noll

Slovak

nula

The
Greek word for zero is μηδεν, read as
'meden', which means, etymologically, not even one (i.e. nothing).
The Oracle of Delphi in ancient Greece had a wise motto, like
this: "meden agan" - nothing too much (or nothing
in excess)... -
posted by George Pantazis

In German,
the expression in Null Komma nichts (in
zero point nothing) means 'in a trice'

In Italian,
the expression a chilometri zero (in
zero kilometers from any location) means 'local'. For instance, un
gelato a chilometri zero translates as 'an ice-cream produced
with local products'.

There
are no letters assigned to the numbers 0 and 1 on
a phone dial. These numbers remain unassigned
because they are so-called 'flag' numbers, kept for special purposes
such as emergency or operator services.

"Wuji" (Number
0), in the Mystical Numbers of Taoism, represents the Null, the
Chaos, the Origin and the End.

Zero
Star Hotel (Null Stern Hotel)
The "Null
Stern", or "Zero
Star" Hotel is a cross between a hostel and an art installation
by Swiss concept artists Frank and Patrik Riklin. This hotel is
actually a converted bomb shelter...

The
population of the Roman Empire under Augustus was
about one hundred millions, of which more than one half were
slaves!

There
is a 1/2 percent probability you are related to Genghis Khan...
An international
group of geneticists studying Y-chromosome data have found
that nearly 8 percent of the men living in the region of the former
Mongol empire carry y-chromosomes that are nearly identical to
those of Genghis Khan, the fearsome Mongolian warrior of the 13th
century, whose adopted name means "Universal Ruler" in
Altaic, his native tongue. That translates to 0.5 percent of the
global population in the world (or roughly 16 million descendants
living today).

Did
you know that the Romans too could transcribe unit fractions?
e.g. to write1/2 they
used the letter S (semis). Knowing that, what represents
the Roman numeral SIX?Obviously
not 6, but 8.5! (10 - 1 - 1/2)

In
Italy, "fojetta" (small leaf, in Roman
dialect) is a measure corresponding to half a liter of
wine.

A
typical 'fojetta' ->

Tupper's
self-referential formula
is an amazing formula concocted by Jeff Tupper that, when graphed
in 2 dimensions, can visually reproduce the formula itself:If one graphs the set of points (x, y)
with 0 < x < 106 and k < y < (k +
17), such that they satisfy the inequality given above, the resulting
self-referential 'plot' looks like this:

1⠼⠁I

is
a separate and special entity called 'Unity' or 'Identity
element'. 1 is actually the identity element under multiplication
for the real numbers, since a x 1 = 1 x a = a.
Mathematicians refers to 1 as the multiplicative identity (or
better said, the reflexive identity of multiplication).

is NOT prime!
Primes or prime
numbers can be poetically described as the 'atoms' of mathematics
- the building blocks of the world of numbers. But, mathematically
speaking: "a prime number is a positive integer with
exactly TWO positive divisors: 1 and itself". Modern
textbooks consider 1 neither prime nor composite, whereas older
texts generally asserted the contrary. In 1859, Henri
Lebesgue stated explicitly that 1 is prime in "Exercices
d'analyse numérique". It is also prime in "Primary
Elements of Algebra for Common Schools and Academies" (1866)
by Joseph Ray, and in "Standard Arithmetic" (1892)
by William J. Milne. A list of primes to 10,006,721 published
in 1914 by Derrick N. Lehmer includes 1 ("List of prime
numbers from 1 to 10,006,721", Carnegie Institution of Washington).

Benford's
law states that in a huge assortment of number sequences
- in listings, tables of statistics, random samples from a
day's stock quotations, a tournament's tennis scores, the populations
of towns, electricity bills in the Solomon Islands, and much
more, the digit 1 tends to occur with probability ∼30%,
much greater than the expected 11.1% (i.e., one digit out of
9). Dr. Nigrini gained recognition by applying a system he
devised based on Benford's Law to some fraud cases in Brooklyn.
The idea underlying his system is that if the numbers in a
set of data like a tax return more or less match the frequencies
and ratios predicted by Benford's Law, the data are probably
honest. But if a graph of such numbers is markedly different
from the one predicted by Benford's Law, he said, "I think
I'd call someone in for a detailed audit".

Mathematicians
define a 'sphere' as the surface of a sphere, not a solid ball,
so a sphere has 2 sides: the outside and the inside. However,
there are also 1-sided
surfaces!

f(x) = ex at the point x = 0 is exactly
1.

=0!
Why 0! = 1? Because 4! = 4x3x2x1 and 3! = 3x2x1. Therefore 4! =
4x3! In the same way 3! = 3x2! and 2! = 2x1! So it follows
that 1! = 1x0! Therefore 0! must be equal to 1 or 1! would
be 0... And so 2! would be zero and then 3! and so on.

During
any police lineup the suspects wear nos. 2 through 9 because
it is considered too suggestive to make anyone display the no. 1!

Symbolizes
the essence of all phenomena, which is a single unity, before
being divided. It represents also the contrast between essence
and existence; the enduring and the ephemeral; the unity in diversity
(one/many). According to Hopper, the first advance towards counting
is with the use of words for one and for many,
the differentiation from the self from the group. We still say
'numero uno' to speak of ourselves.

"Taiji" (also
termed as "Dayi" or "Taiyi"), in the Mystical
Numbers of Taoism, represents the ONE, the Ultimate, the Order.
The martial art known as "Taijiquan" based its movement's
philosophies upon the notion of Taiji.

In
the English language, there is a word with just ONE vowel which
occurs 6 times: indivisibility.

'Strengths'
is the longest word in the English language with just ONE vowel.

Impoverished
counting system: 1 + 1 = ?
When it comes to counting, a remote Amazonian tribespeople have
been found to be lost for words. In fact, researchers discovered
that Pirahã tribe
of Brazil, with a population of 200, have no words beyond ONE,
two and many.
The word for "one" can also mean "a few", while "two" can
also be used to refer to "not many"... (But is there
any case where not having words for something doesn't allow you
to think about it?) Source BBC

One
of the earliest numerical approximation of 2 was
found on a Babylonian
clay tablet (from the Yale Babylonian Collection), dated
approximately to between 1800 B.C. and 1600 B.C. The annotations
on this tablet give an impressive numerical approximation in
four sexagesimal figures:
1 + 24/60 + 51/602 + 10/603 = 1.41421296...

ISO
paper sizes are all based on a single aspect ratio of the square
root of two, or approximately 1:1.4142. Basing paper upon this
ratio was conceived by Georg Lichtenberg in 1786, and at the
beginning of the 20th century, Dr Walter Porstmann turned Lichtenberg's
idea into a proper system of different paper sizes.

1.62

is
the Golden Number,
also called Golden Ratio or Phi.
Golden Number property: ( +
1)/ = /1

Remarkably,
you can use Fibonacci
successive terms to convert miles to kilometers:
8 miles ≈ 13 kilometers
13 miles ≈ 21 kilometers
This works because the two units stand in the Golden Ratio (to
within 0.5 percent).

The
3184th Fibonacci number is an apocalypse number (Apocalpyse numbers
are numbers having exactly 666 digits).

π2/61.64

≈ 1.644934066848226436472

The “Basel
Problem” asks for the exact sum of the reciprocal
square series:
1 + 1/22 + 1/32 + 1/42 + 1/52 +
... + 1/(n-1)2 + 1/n2
as well as a proof that this sum is correct. The Swiss mathematician Euler found
the exact sum to be π2/6 and
announced this discovery in 1735. The value is denoted by λ (lambda)
and seems to appear everywhere in mathematics. In fact, the probability
that a randomly chosen integer is not divisible by a square (square-free)
is 1/λ or 6/π2

1.73

is
also known as Theodorus' constant (it is named after Theodorus of
Cyrene, who proved that the square roots of the numbers from
3 to 17, excluding 4, 9, and 16, are irrational).
is the diagonal of a cube having 1-unit sides.
is the height of an equilateral triangle having 2-unit sides.

The
shape 'Vesica
piscis' (fish bladder) has a major axis/minor axis ratio
equal to the square root of 3, this can be shown by constructing
two equilateral triangles within it.

25·92 = 2592,
the only 4-digit number of the form ABxCD=ABCD.
The only other known number that shares this property is 24547284284866560000000000
= 24·54·72·84·28·48·66·56·00·00·00·00·00.
Such numbers arec called narcissistic
numbers.

27 = 712 -
173

is
the smallest prime that can grow 7 times by the right:2 is prime,29 is prime,293 is prime,2939 is prime,29399 is prime,293999 is prime,2939999 is prime. 29399999 is prime.

Tetration: nn =
2, when n is about 1.559610469... (which is a transcendental
number)

When
you increase the area of a square of 1 unit-square, the side n of
this square - for n > 3 - increases approximately
of 1/2n. For example: (12 +
122) ≈ 12 + 1/(2 x 12) ≈ 12.0416... -
G. Sarcone

"Liangyi" (Number
2), in the Mystical Numbers of Taoism, symbolizes the Twin, the
First Division, the Duality of Opposites (Yin/Yang).

In
Cantonese the number two is fortunate, because it sounds similar
to "easy" in the dialect.

In
pre-1972 Indonesian and Malay orthography, the digit 2 was
shorthand for the reduplication that forms plurals, for instance: orang "person",
and orang-orang or orang2 "people".
This orthography has resurfaced widely in text messaging and
other forms of electronic communication.

The two-second
rule is an easy way to make sure you have left enough
following distance between your car and the vehicle in front,
no matter what speed you're travelling at. To check if you
are travelling two seconds behind the vehicle in front:
- watch the vehicle in front of you pass a landmark (such as a
sign, tree, or power pole) at the side of the road,
- as it passes the landmark, start counting 'One thousand and one,
one thousand and two',
- if you pass the landmark before you finish saying those eight
words, you are following too closely. Slow down, pick another landmark
and repeat the words to make sure you have increased your following
distance. -- Source Land
Transport NZ.

is
an irrational number involved in the formula for the Golden
ratio.
is also used in statistics when dealing with 5-business day weeks.
is the hypothenuse of a right triangle having 1 and 2-unit sides.
is the diagonal a rectangular box having 1, 2
and 2-unit
sides.

is
the only prime 1 less than a perfect square. -
Robin Regan
is the number of spatial dimensions needed to mathematically describe
a solid.
are the primary colors.

are
the geometric constructions you cannot build using just a ruler
and compasses: 1. You cannot trisect - divide into three equal
parts - a given angle; 2. Double a cube; and 3. Square a circle.

A number
is divisible by 3 when the sum of its digits can be divided by
3.

If the
denominator of a rational number is not divisible by 3,
then the repeating part of its decimal
expansion is an integer divisible by 9. Example: 1/7 = 0.142857...
has a repeating part '142857' divisible by 9. Another example
with a larger recurring
decimal: 1/23 = 0.0434782608695652173913... has a repeating
part '0434782608695652173913' divisible by 9.

3
is the minimum colors needed to create camouflage patches, usually
used in military compounds and vehicles. -
posted by George Pantazis

38

31

36

33

35

37

34

39

32

The
product of the 3 numbers in each row, column, or diagonal
of the geometric magic
square opposite - involving powers of 3 - gives the magic
constant 14,348,907. Moreover, the exponents are arranged
the same as in the normal 3x3 magic square!

A
3 x 3 alphamagic
square is a magic
square for which the number of letters in the word for each
number generates another magic square, for instance:

5

22

18

28

15

2

12

8

25

five (4)

twenty-two (9)

eighteen (8)

twenty-eight (11)

fifteen (7)

two (3)

twelve (6)

eight (5)

twenty-five (10)

A 3 x
6 rectangle has an area equal to its perimeter.

In
one gram of water the number of molecules is about:
3.3 x 1022 = 33000000000000000000000

The balanced
ternary base, is a numeral system which uses 3
values or digits: -1, 0, and 1. It works as follows
(in the example, the symbol 1 denotes the digit -1):

Decimal

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

Balanced
ternary

110

111

11

10

11

1

0

1

11

10

11

111

110

111

Ternary
or base-3 numbers can
be converted to balanced ternary notation by adding 1111... with
carry, then subtracting 1111... without borrow. For instance:
0213 + 1113 = 2023, 2023 -
1113 = 1113(bal) = 710This
non-standard positional numeral system is easily represented as
electronic signals, as potential can either be negative, neutral,
or positive (comparison logic). The balance ternary system is also
useful to solve the classical 2-pan
balance puzzle.

3 hundred
millions of Indians live with less than 1 dollar per day (2004).

Non-paternity
rates: statistically, one in three men who ask
for paternity
test turn out not to be the biological parent.

An octopus
has 3 hearts.

The
number 3 symbolizes the principle of growth. In Guangdong province,
China, three is associated with living or giving birth.

"Sanqing" (also
known as "Sanxing" or "Sancai"), in the Mystical
Numbers of Taoism, represents the number 3 and symbolizes the
Three Luminaries: Sun, Moon, Stars. It also defines the concept
of "Heaven, Mankind, Earth" as well as "Upper,
Centre, Lower".

Deep
thought: "There are 3 kinds of people: those who can count
and those who can't".

If
you’re a Simpsons fan, then you problably know about “Blinky”,
the three-eyed
fish found near the nuclear plant where Homer Simpson was
working. As it turns out, the Simpsons were right yet again,
as fishermen in Córdoba, Argentina caught a three-eyed
wolf fish in a reservoir fed by a local nuclear power plan! (Fri,
Oct 28, 2011)

In
the taoist mythology, Erlang Shen (二郎神),
or Erlang is a Chinese God with a third truth-seeing
eye in the middle of his forehead.

In
the late 18th century, James Stirling, a Scottish mathematician,
developed an approximation for factorials using the transcendental
numbers 'Pi' and 'e':
n! ≈ (2n)1/2 (n/e)n

The
most famous formula for calculating Pi is Machin's formula:/4
= 4 arctan(1/5) – arctan(1/239)This formula, and similar ones, were used to push
the accuracy of approximations to Pi to over 500 decimal places
by the early 18th century (this was all hand calculation!).

Amazing
pandigital approximation of by
mathematician E. Pegg:0 + 3 + [1 - (9 - 8-5)-6]/(7 + 2-4)A
number or a formula is said to be "pandigital" if it
contains each of the digits from 0 to 9. You can discuss this here.

Interestingly,
there are no occurrences of the sequence 123456 in the first
million digits of Pi. -
posted by George Pantazis

We use
Pi to:
- describe the DNA double helix,
- determining the distribution of primes - the probability that
two randomly selected integers are relatively prime (i.e. have
no common factors) is 6 / p2,
- analyzing the ripples on water,
- checking for accuracy - as there are now millions upon millions
of known decimal places of Pi, by asking a super computer to compute
this many figures its accuracy can be tested,
- in cryptography - the science of coding,
- generate of a random number.

On Pi
Day (March 14 or 3-14) in 1879, a baby was
born in Ulm, Germany to a German couple whose name meant "one
stone". That baby was Albert Einstein!

occurs
naturally in tables of death, in what is known as a Gaussian
distribution of deaths in a population; that is, when a person
dies, the event 'feels' Pi.

The
symbol for Pi was introduced by the English mathematician William
Jones in 1706.

Mathematician
John Conway pointed out that if you break down the digits of
Pi into blocks of ten, the probability that one of those blocks
will contain ten distinct digits is about one in 40,000. Curiously,
this first happens in the 7th block of ten digits.

There
is the little rhyme to help the memorisation of twenty-one digits
of :Now, I wish I could recollect pi.
"Eureka," cried the great inventor.
Christmas Pudding; Christmas Pie
Is the problem's very center.

Joke:
A round pizza with radius 'z' and thickness 'a' has the volume Pi·z·z·a.

is
the smallest number of colors sufficient to color all planar
maps with no adjoining countries sharing the same color.
are the number of coordinates needed to describe an event in 'spacetime':
t, x, y, z.

Pick
any whole number... If the number is even, divide it by 2; if
it is odd, multiply it by 3, then add 1. By repeating this procedure,
sooner or later you'll arrive at the number 4,
which will give you 2, which in turn gives you 1, and then get
a 4 again! No matter what number you choose, you'll always arrive
at the 4-2-1 cycle.

The
word 'four' has 4 letters and is the smallest honest
number. Honest numbers are numbers n that can be
described using exactly n letters in standard mathematical
English.

A
famous riddle: Show how one-half of five is four!
Answer: Take off the first and last letters and you have the roman
numeral for 4. The Roman numeral for four is IV (whose
letters are one-half of the four letters in the spelled-out word "five").

Why
is the Roman numeral IIII used instead of IV on
clocks and watches?
- using IIII brings more symmetry and balance to the dial. The
IIII offsets the heavy VIII that is found on the other side.
- the strict use of IV instead of IIII wasn't common until after
the middle ages (the practice of placing smaller digits before
large ones to indicate subtraction came into popularity in Europe
after the invention of the printing press), the Romans generally
used IIII. Clocks and watches are patterned after sundials, which
were in use long before the middle ages.

Berger’s
4:9 theoryIn
his book "Bauwerk und Plastik des Parthenon, in Antike Kunst" (Basel,
1980). E. Berger presents a study that investigates the way that
the Pythagorean ideas of ratios of small numbers were used in the
construction of the Temple
of Athena Parthenos. In his opinion the ratio 4 : 9 were fundamental
to the construction. A basic rectangle of sides 4 and 9 was constructed
from three rectangles of sides 3 and 4 with diagonal 5 (see drawing).
This form of construction also meant that the 3-4-5 Pythagorean
triangle could be used to good effect to ensure that right angles
in the building were accurately determined.
The length of the Temple of Athena Parthenos is 69.5 m, its width
is 30.88 m and the height at the cornice is 13.72 m. To a fairly
high degree of accuracy this means that the ratio width : length
= 4 : 9 while also the ratio height : width = 4 : 9.- Source: Article by
J.J. O'Connor and E.F. Robertson.

The four-second
rule is the amount of time that internet user will
wait for a page to load before leaving and going to another
site.

Swear
number:
The phrase "four-letter word" is used
to describe most swear words in the English language.
The Pythagorean
oath, as quoted by the Renaissance magician Cornelius Agrippa,
is as follows:
"I with pure mind by the number four do swear;
That's holy, and the fountain of nature
Eternal, parent of the mind..."

In Japan
and in most Asiatic cultures, the number 4 (sinograph: 四)
is considered unlucky because it is prounounced shi which
sounds like the word 'death'. Due to that, many numbered product
lines skip the number 4. However, in some cases the word yon ('4'
in early classical Japanese) is used instead of shi:
when counting floors in a building, or when you are asked "which
floor?" in an elevator... The aversion or fear of the number
4 is called "Tetraphobia".

Curiosity:
Think of any number and write it out in WORDS. Count the number
of letters it contains and write that down in WORDS. And so
on:
• TWENTY-EIGHT (11 letters) ->
• ELEVEN (6 letters) ->
• SIX (3 letters) ->
• THREE (5 letters) ->
• FIVE (4 letters) ->
• FOUR (4 letters) -> etc.
You will always arrive at FOUR!

A dollar
bill can be double folded (forward and backwards) 4x103 times
before it will tear.

STA4NCE
= For instance!

In Italian,
the expression in quattro e quattr'otto (in
four and four eight) means 'in a trice'.

4
rivers are mentioned in the Old Testament, Gen 2, 10:
"And a river went out of Eden ... and parted ... into four heads. The ...
first [is] Pison ... which compasses the whole land of Havilah ... the
second [is] Gihon ... that compasses the whole land of Ethiopia ...
the third [is] Hiddekel ... that goes toward the east of Assyria ...
and the fourth [is] Euphrates that goes eastward to Assyria".

The
number 4 symbolizes the principle of putting ideas into form.
It signifies work and productivity.

1
in 4 people worldwide is Muslim, and 2 out of
3 of the world's Muslims are in Asia (data: 2009).

is
the only prime number that ends in 5.
is the number of Platonic
solids.
is the only prime number that ends in 5.
is a congruent
number because it is the area of a 20/3, 3/2, 41/6 triangle
(a congruent number is an integer that is the area of a right triangle
with three rational number sides).

The
Roman numeral for 5 is V, which comes from a
representation of an outstretched hand.

Any
power of 5 ends in a 5 (except 50).

= 32 -
22= 12 +
22= 25 -
3352 =
2552 = 32 + 42 = 132 -
122

= (11
x 11 - 11)/(11 + 11)
= D/C

19/95
= 19/95
= 1/526/65
= 26/65
= 2/5

(5 -
1)! + 1 = 0 (mod 52)

Any
number having a abc5abc5 pattern
is divisible by: 5, 73, 137, and 10001

Can
you count in 'ding-bong'?The
inhabitants of 'Fongaponga' use a series of sounds made from this
strange device to represent numbers: 'ding'
with the handbell, 'eek' when squeezing the rubber
bulb of the horn, and 'bong'
when beating the tambourine with the small ball. These very special base-5
numerals are then strings made from 3 sounds each
corresponding to an additive numerical value. Looking at the number
list below, we can guess with the help of some logic that 'eek'
is actually a 'function' that indicates subtraction and that every
'ding' equals 5, and every 'bong', 7.

A five-sided
polygon (pentagon) has 5 diagonals. This is the only shape for
which the number of sides and diagonals is the same (which may
explain why pentagrams, pentacles, and pentangles are
so common and appear so often as iconographic symbols). -
by Patrick Vennebush -

Pentagram, Pentangle and Pentacle are
all names for a 5-pointed star. This mystical symbol is supposed
to keep away devils and witches.

Early
Greek coin marked with Quincunx Pattern

The number
5 is geometrically represented in the Quincunx pattern.
This design is arranged by marking four corners of an imaginary quadrilateral
and a central axis through a series of dots or objects - as noticed
on dice, playing cards, or dominoes. The significance of the quincunx
pattern originates in Pythagorean mathematical mysticism.

A
famous riddle involving 5s: How can you make the following
equation true by drawing only one straight line:
5+5+5=550
Answer:
545+5=550

Another
famous riddle: From a word of 5 letters,
take 2 letters and have 1.
Answer: ALONE - AL = ONE.

In
French "je te dis un mot de cinq lettres!" (I tell
you a word of five letters) is an exclamation of anger against
the person for whom the insult is intended.

5th
April
At 1:02 AM and 3 seconds on Wednesday, April 5, 2006, it was the
1st hour of the day, the 2nd minute of the hour, the 3rd second
of that minute in the 4th month and the 5th day of '06... or just: 01:02:0304-05-06 for
short!
For many other places, this coincidental chronological oddity happens
at 1:02 AM May 4.

The
five rivers of Hades are:
• Acheron (the river of woe. Etymologically,
the name probably means 'marsh-like': cf. Greek word akherousai, 'marshlike
water'),
• Cocytus (the river of lamentation; from Greek kokutos,
'lamentation'),
• Phlegethon (the river of fire; from Greek present
participle of phlegethein, 'to blaze'),
• Lethe (the river of forgetfulness; from Greek lethe,
'forgetfulness')
• Styx (the river of hate; cognate with Greek
words stygos 'hatred' and stygnos 'gloomy').

Five
is a very popular number in Chinese culture since it occupies
the central position (one through nine) and also reflects the
'Five Elements Philosophy' (Wuxing) - Wood, Fire, Earth, Metal
(or Gold), and Water (in Chinese: 木, mù; 火,
huǒ; 土, tǔ; 金, jīn; 水, shǔi).

In Switerland,
the banking sector employs about 5% of the workforce
(data: 2005).

According
to a research by Commtouch, quoted by NYT, only 5 countries:
China, South Korea, Russia, USA and Brazil generate 99% of spams.

The
name Pontius (Pilatus), in early Italic language means
'the 5th'. We can find the Indo-european root penkwro,
the '5th', in the word finger (finger, from
Germanic fingwraz,"one of five").- by Gianni A. Sarcone -

Macuilxochitl was
the god and patron of art, games, beauty, dance, flowers, and
song in Aztec mythology. His name contains the Nahuatl words xochitl ("flower")
and macuil (five), and hence means "Five-flower" (but
he could also be referred to as Chicomexochitl, "Seven-flower").

The
number 5 (๕) is
pronounced as 'Ha' in Thai language.
555 is also used by some as slang for 'HaHaHa'!

Soup
5, variously spelled 'Soup Number Five' or 'Soup #5',
is a soup made from bull's testicles or penis.The dish originates
from Filipino cuisine. It is believed to have strong aphrodisiac
properties.

Joke
For those who know German:
- Mr. Freud, what is between fear and sex?
- FŁnf!

is
a congruent
number because it is the area of a 3, 4, 5 triangle (a congruent
number is an integer that is the area of a right triangle with
three rational number sides).
is the smallest perfect
number, that is a number whose divisors add up to itself, e.g.:
1 x 2 x 3 = 1 + 2 + 3 = 6

The
probability that a number picked at random from the set of integers
will have no repeated prime divisors is 6/2.
- Source:
Chartres

n3 - n is
divisible by 6. That is, any product of 3 consecutive integers
is divisible by 6.
The equation xn - ym = ±6 with n, m > 1
has NO solution. In other words, 6 cannot be a
difference of two powers!

A
Simple Mnemonic Math Trick
When you multiply 6 by an even number, they both end in the same
digit.
Example: 6x2=12, 6x4=24,
6x6=36, 6x8=48,
etc.

6 is
the smallest number of colors needed to color the regions on
a map on a Möbius
strip. A Möbius strip is a continuous closed surface
with only one side; formed from a rectangular strip by rotating
one end 180 degrees and joining it with the other end.

6
circles of the same size (try this with 6 coins of the same denomination)
will always perfectly surround, all touching, without gaps, 1
circle of that same size. - Posted by Aaron
Pyle

The
probability to get one 6 with 6 dice is 0.665...
The probability to get two 6's with 2 x 6 = 12
dice is 0.619...
The probability to get three 6's with 3 x 6 =
18 dice is 0.597...

Arithmetical
nut with 6: "From six take nine; from nine
take ten; from forty take fifty, and have six left" (see
below)

SIX
IX

IX
X

XL
L

S

I

X

A base-6
(senary or heximal) numeral system is used by the Ndom people
of the Frederik Hendrik Island, near New Guinea. For example,
in Ndom language the number 7 is mer abo sas (6 + 1),
and the number 17, mer an thef abo meregh (6 x 2 + 5).

"This
exclamation has unexpectedly six 's',
six 'i' and six 'x'!" (autoreferential
sentence) - G. Sarcone.

Any
one of us is only about 6 acquaintances away from anyone else
in the world.

Brazilians
have two different names for six: seis or meia (short
for meia duzia, 'half dozen').

In
old French, the word 'hasart' meant 6 at the
game of dice. The earliest meaning of HAZARD (<hasart) was,
however, 'stroke of luck (or bad luck)'. In the past, the dice
featured on one face a flower pattern. Thus the Arabs called
gaming dice "flowers", in Arabic 'az-zahr'.

the "sixth
sick sheik's sixth sheep's sick" is said to be
the hardest tongue twister in English.

Riddle:
can you transform the Roman number IX into 6 by
drawing only one line?
Answer: SIX (yes, the line is curvilinear...).

Joke.
Solving the equation by one dumbo:

Chinese
people like the number 6. One possible reason is because it is
the largest number on a dice, and when gambling, one wins if
the number six is thrown. When playing mah-jong, the host is
the most likely to be the one who throws the number six, and
who therefore has a better chance of winning. Reflecting this,
the Chinese have a saying, "double six makes you the happiest".
For Chinese businessmen the number six means "a smooth business".

When
a Yoruban
man in Nigeria get really attracted to a woman, he sends six shells
to her. In fact, the Yoruban word efa means both 'six'
and 'attracted'. If this chat up line works, the girl replies
with eight shells - ejo meaning both 'eight' and 'I
agree'!

6
persons
Whenever two people meet, there are really six people
present. There is each man as he sees himself, each man as the
other person sees him, and each man as he really is.
-- William James.

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